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| United States Patent |
5,270,380
|
|
Adamson
, et al.
|
December 14, 1993
|
Method for extending the open time of an aqueous coating composition
Abstract
A method for extending the open time of an aqueous coating composition is
provided. This method extends the time during which an aqueous coating can
be applied or rebrushed without damaging the film. The open time
improvement of this invention is useful for a variety of coatings
including paints, stains, varnishes, adhesives, and inks. The aqueous
coating composition contains a latex polymer and a modifying compound.
More particularly, the latex polymer contains a first reactable group
which is complementary to and reacts with a second reactable group in the
modifying compound. The complementary reactable groups in the latex
polymer and modifying compound provide ionic or covalent binding.
| Inventors:
|
Adamson; Linda A. (East Greenville, PA);
Merritt; Richard F. (Fort Washington, PA);
Nkansah; Asare (Lansdale, PA);
Lee; Jungsik (Horsham, PA)
|
| Assignee:
|
Rohm and Haas Company (Philadelphia, PA)
|
| Appl. No.:
|
959879 |
| Filed:
|
October 13, 1992 |
| Current U.S. Class: |
524/556; 524/557; 524/559; 524/560; 524/561; 524/562; 524/563; 524/564; 524/803; 524/804 |
| Intern'l Class: |
C08L 075/04 |
| Field of Search: |
524/556,557,559,560,561,562,563,564,803,804
|
References Cited
U.S. Patent Documents
| 4647610 | Mar., 1987 | Sperry et al. | 524/377.
|
| 4923514 | May., 1990 | Brown | 524/242.
|
| 4952622 | Aug., 1990 | Chauvel et al. | 524/376.
|
Primary Examiner: Welsh; Maurice J.
Attorney, Agent or Firm: Vouros; James G.
Claims
What is claimed is:
1. A method for extending the open time of an aqueous coating comprising:
(a) selecting a latex polymer with a first reactable groups;
(b) selecting a modifying compound with a second reactable group which is
complementary to the first reactable group in the latex polymer;
(c) forming an aqueous coating by combining the latex polymer and modifying
compound; and
(d) applying said aqueous coating composition to a substrate.
2. An aqueous coating composition having extended open time comprising a
latex polymer and a modifying compound where the latex polymer consists of
a first reactable group which is complementary to and combined with a
second reactable group in the modifying compound.
3. A method of using a modifying compound containing a reactable group for
extending the open time of an aqueous coating composition containing a
latex polymer having a reactable group which is complementary to the
reactable group in the modifying compound.
4. The method of claims 1 or 3 and the coating composition of claim 2 where
the concentration of the modifying compound is from 0.1 to about 10
percent by weight solids, based on the total weight solids of the latex
polymer in the aqueous coating composition.
5. The composition of claim 2 where the modifying compound is an
amphiphilic compound further comprising a hydrophobic portion with at
least 4 carbon atoms.
6. The composition of claim 5 where the amphiphilic compound has a weight
average molecular weight less than about 10,000.
7. The composition of claim 5 where the complementary reactable groups in
the latex polymer and amphiphilic compound are an ionizable pair selected
from the group consisting of positively and negatively charged atoms, and
acids and bases.
8. The composition of claims 1 or 2 where the complementary reactable
groups in the latex polymer and modifying compound are selected from the
group consisting of:
(a) acetoacetate-aldehyde;
(b) acetoacetate-amine;
(c) amine-aldehyde;
(d) amine-anhydride;
(e) amine-isocyanate;
(f) amine-epoxy;
(g) aldehyde-hydrazide;
(i) acid-epoxy;
(j) acid-carbodiimide;
(k) acid-chlor methyl ester;
(m) acid-anhydride;
(n) acid-aziridine;
(o) epoxy-mercaptan; and
(p) isocyanate-alcohol,
wherein a group in each pair is present in the latex polymer and the
complementary reactable group is present in the modifying compound.
9. The composition of claim 5 where the latex polymer comprises from 0.5%
to about 10% by weight of the total composition of an ionizable acid
group.
10. The composition of claim 5 where the latex polymer comprises from 0.5%
to about 5% by weight of the total composition of an ionizable acid group.
11. The latex polymer of claims 1 or 2 is a polymer selected from the group
consisting of acrylic, styrene acrylic, stryene butadiene, and vinyl
acetate polymeric latexes.
12. The latex polymer of claim 10 where the latex polymer has an average
particle size from about 30 to about 800 nanometers.
13. The composition of claim 11 where the latex polymer has an average
particle size from about 90 to about 500 nanometers.
14. The method of claim 1 where the aqueous coating comprises the second
reactable group in the modifying compound covalently bonded to the
complementary first reactable group in the latex polymer.
Description
FIELD OF THE INVENTION
This invention relates to a method of increasing the time that an aqueous
coating remains workable after it has been applied to a substrate. The
method requires forming an aqueous coating by combining a selected
modifying compound and a latex polymer, and applying the coating so formed
to a substrate. More particularly, the modifying compound and the latex
polymer contain complementary reactable groups. This invention also
relates to the aqueous coating composition which remains workable after it
has been applied to a substrate.
BACKGROUND OF THE INVENTION
Aqueous dispersions containing polymers such as paints, stains, adhesives,
and printing inks are being increasingly used because of their safety,
economy, ease of application, and ease of clean-up. Aqueous coatings such
as latex paints, dry quickly compared to solvent coatings such as alkyd
paints. Because of the faster drying time of aqueous coatings relative to
solvent coatings, a second coat can be applied in a short time, for
example, from about 3 to about 5 hours. However, because of the fast
drying nature of aqueous coatings, there is often not enough time to
rebrush over the freshly coated wet surface to improve its appearance or
to apply additional paint onto the freshly coated wet surface without
causing defects such as brush marks, loss of gloss, or lap lines in the
final dried coating. A "lap" as used herein, refers to an area on a
substrate where additional coating is applied onto a portion of a
previously coated, but still wet, adjacent substrate area.
In the case of paint, it is desirable to seamlessly join up the edges of a
wet painted area with newly added fresh paint without any visible lap
showing in the dried coating. "Lapping" or "to lap" refers to the ability
to do this seamless joining of edges without leaving a visible "lap" line.
As used herein, "open time" or "wet-edge time" refers to the time that a
coating remains workable, after it has been applied to a substrate, to
allow for rebrushing or "melting in" of the newly applied coating at the
lap, without resulting in the above defects. Open time is a more apparent
problem in cases where other than a flat or dull surface appearance is
desired, such as with sheen and gloss paints, because a glossy appearance
makes the surface defects more visible.
During the drying of the aqueous coating, as water evaporates, latex
polymer particles deform and fuse together to form a continuous film. This
process, known as "film formation" or "coalescence", is irreversible since
the addition of water onto the dried or drying coating will not redisperse
the polymer particles. Once coalescence occurs, it is impossible to
rebrush the aqueous coating and lap into a previously coated area.
The drying characteristics of aqueous coatings such as dry time, flow and
gloss of the dried coating, are not easily controlled, because they are
dependent on how fast the water in the coating evaporates. The drying
behavior of aqueous coatings depends on the temperature, humidity and air
velocity at the time of application and thereafter. For example, coatings
can dry almost instantaneously under hot, dry, or windy conditions leading
to poor lapping characteristics and short open times. In addition, these
conditions tend to also impair the quality of film formation which can
result in cracks, poor flow, low gloss, and poor adhesion to the
substrate.
Polymeric compositions dispersed in organic solvents have different drying
characteristics than the aqueous polymeric coatings because solvents or
solvent blends tend to have a wide range of boiling points and evaporation
rates compared to water. This range of boiling points can be used to
modify the drying characteristics of the solvent based coating according
to the specific application requirements. For example, alkyd paints are
made with hydrocarbon solvents which are selected so that the drying rate
is sufficient to minimize sagging, running, and dust pickup, while
permitting good "melting in" at the lap. The disadvantages of such organic
solvent based coatings include the difficulties in clean-up, the toxic
nature of organic solvents, pollution, odor, stickiness of the dried paint
film, such as for example, tack, and the relatively high cost of organic
solvents.
The conventional practice for addressing the quick drying nature of aqueous
coatings has been to add substantial levels of water-soluble solvents,
such as for example, 10 to 20 percent or more based on total liquid
content, to such coatings to increase the open time. These techniques are
discussed by M. D. Andrews, "Influence of Ethylene and Propylene Glycols
on Drying Characteristics of Latex Paints," Journal of Paint Technology,
vol. 46, page 40 (1974); D. A. Sullivan, "Water and Solvent Evaporation
from Latex and Latex Paint Films," Journal of Paint Technology, vol. 47,
page 60 (1975); and C. R. Martens, Waterborne Coatings, Van Nostrand
Reinhold, page 153 (1981). These references discuss the use of short chain
water-soluble alcohols and glycols as cosolvents in aqueous coatings to
aid coalescence of the latex particles, improve leveling, and prolong open
time. However, these cosolvents negate the intrinsic advantages of aqueous
coatings such as safety, low tack, low odor, and low pollution.
DESCRIPTION OF THE PRIOR ART
Another approach for increasing the open time of aqueous coatings has been
the use of surface active evaporation suppressants to control water
evaporation. U.S. Pat. No. 4,647,610 discloses a method of reducing the
evaporation rate of water from aqueous polymeric coatings, such as latex
coatings, by incorporating low levels of surface-active, aliphatic
compounds having a saturated, unbranched carbon-carbon chain length of
about 16 atoms or greater, and containing one or more hydrophilic groups.
The evaporation suppressants preferably include the long, straight-chain
alcohols, ether alcohols, and salts of carboxylic acids. These alcohols
and salts are believed to increase the open time of an aqueous coating by
reducing the rate of evaporation of water through the formation of highly
compact and dense monolayers at the air/water interface. The '610 patent
does not teach a method of increasing the open time of an aqueous coating
formed with a modifying compound that is complementary to and reacts with
the latex polymer.
U.S. Pat. No. 4,952,622 discloses the preparation of polymer particles
which carry, implanted on their surface, amphiphilic molecules with
ion-forming or reactive groups. The process requires contacting a latex of
particles with an amphiphilic compound within the glass transition zone of
the polymer, until the hydrophobic block of the amphiphilic compound is
"enmeshed" with the macromolecular chains of the polymer. The '622 patent
discloses the use of these particles and their dispersions in biological
applications but does not disclose or suggest that these particles could
be used to improve the open time of an aqueous coating.
SUMMARY OF THE INVENTION
This invention relates to a method of extending the open time of an aqueous
coating containing a latex polymer. The method requires selecting a latex
polymer having a first reactable group and selecting a modifying compound
containing a second reactable group which is complementary to the first
reactable group in the latex polymer, forming an aqueous coating by
combining the modifying compound and the latex polymer, and applying the
aqueous coating so combined to a substrate. This invention also relates to
the aqueous coating composition having extended open time.
DETAILED DESCRIPTION OF THE INVENTION
This invention is directed to a method of extending the open time of an
aqueous coating containing a latex polymer, such as for example, latex
paints. The open time improvement of this invention is also useful with
other aqueous polymeric coating compositions such as for example, paints,
stains, varnishes, adhesives, and inks. This invention requires an aqueous
coating containing a latex polymer and a selected modifying compound
having complementary reactable groups. The polymers which can be employed
in the aqueous coating include, for example, emulsion polymers, and
colloidal dispersions, such as those described by C. R. Marten, Waterborne
Coatings, Van Nostrand Reinhold, pages 41-51 (1981).
The complementary reactable groups in the latex polymer and modifying
compound provide ionic or covalent binding. Complementary ionic binding
includes acid-base interaction and ion pair binding of negatively and
positively charged atoms.
Covalent binding by complementary reactable groups may include:
(a) acetoacetate-aldehyde;
(b) acetoacetate-amine;
(c) amine-aldehyde;
(d) amine-anhydride;
(e) amine-isocyanate;
(f) amine-epoxy;
(g) aldehyde-hydrazide;
(i) acid-epoxy;
(j) acid-carbodiimide;
(k) acid-chloro methyl ester;
(l) acid-chloro methyl amide;
(m) acid-anhydride;
(n) acid-aziridine;
(o) epoxy-mercaptan; and
(p) isocyanate-alcohol.
The first or second reactable group in each pair may be present in the
latex polymer or in the modifying compound.
The latex polymer is an emulsion polymer having at least one reactable
group. In addition, the latex polymer may contain more than one reactable
group. More preferably, the latex polymer is an emulsion polymer with a
reactable ionizable acid group such as for example, acrylic, methacrylic,
itaconic, aconitic, citraconic, crotonic, maleic, fumaric, the dimer of
acrylic acid, vinyl sulfonic acid, acrylamido-2-methylpropanesulfonic acid
(AMPS), phosphonoethyl methacrylate (PEM), sulfonoethyl methacrylate (SEM)
and so on.
Suitable emulsion polymers useful in the aqueous coatings of this invention
may be made by conventional emulsion polymerization techniques well known
in the art. It is preferred that the latex polymer is an emulsion
homopolymer or copolymer, more preferably an emulsion polymer formed from
a vinyl monomer, such as vinyl acetate, an acrylic monomer, or a styrenic
monomer, such as those typically used in making water based paints,
stains, adhesives, and varnishes.
The preferred latex polymers include homopolymers and copolymers of: (1)
vinyl esters of an aliphatic acid having 1 to 18 carbon atoms, most
preferably vinyl acetate; (2) acrylic acid esters and methacrylic acid
esters of an alcohol having 1 to 18 carbon atoms, most preferably methyl
acrylate, ethyl acrylate, butyl acrylate, 2-ethylhexyl acrylate, methyl
methacrylate, ethyl methacrylate and butyl methacrylate; and (3) mono-and
di-ethylenically unsaturated hydrocarbons, such as ethylene, isobutylene,
styrene, and aliphatic dienes, such as butadiene, isoprene, and
chloroprene.
The vinyl esters include poly(vinyl acetate) and copolymers of vinyl
acetate with one or more of the following monomers: vinyl chloride,
vinylidene chloride, styrene, vinyltoluene, acrylonitrile,
methacrylonitrile, one or two of the acrylic and methacrylic acid esters
mentioned. Similarly copolymers of one or more of the acrylic or
methacrylic acid esters mentioned above with one or more of the following
monomers: vinyl acetate, vinyl chloride, vinylidene chloride, styrene,
vinyltoluene, acrylonitrile, and methacrylonitrile are also conventionally
used in water based paints. Homopolymers of ethylene, isobutylene, and
styrene, and copolymers of one or more of these hydrocarbons with one or
more esters, nitriles or amides of acrylic acid or of methacrylic acid or
with vinyl esters, such as vinyl acetate and vinyl chloride, or with
vinylidene chloride are also used. The diene polymers are generally used
in water based paints in the form of copolymers with one or more monomers
following: sytrene, vinyltoluene, acrylonitrile, methacrylonitrile, and
the above mentioned esters of acrylic acid or methacrylic acid. In a
preferred embodiment of this invention, a small amount, such as from 0.5
to 5.0 weight % or more, preferably about 1.0 weight %, of an acid monomer
is included in the monomer mixture used for making the copolymers. Acids
used include acrylic, methacrylic, itaconic, aconitic, citraconic,
crotonic, maleic, fumaric, the dimer of acrylic acid, and so on.
The latex polymer can also be a sequential emulsion polymer, such as for
example, a core/shell polymer with the reactable group located on the
shell or the relatively more hydrophilic portion of the polymer.
Most preferably, the latex polymer is an anionically stabilized emulsion
polymer with a negative surface potential of -10 millivolts and higher
(higher as used herein means more negatively charged, such as for example,
-20 millivolts), as determined by zeta potential measurements.
The average "particle size" or diameter of the emulsion polymer may be from
about 30 to about 800 nanometers, more preferably from about 90 to about
500 nanometers, and most preferably about 200 nanometers. The "particle
size", as used herein, is the weight average diameter expressed in
nanometers, can be determined by electron microscopy. In general, the
molecular weights of these emulsion polymers are typically from about
100,000 to 5 million weight average and most commonly above 500,000.
The modifying compound must contain at least one water soluble group which
includes, for example, polyoxyethylene, polyvinyl alcohol, polyacrylamide,
poly N-vinyl pyrrolidone, or a natural polymer such as starch. The
modifying compound must also contain a second reactable group which is
complementary to the first reactable group in the latex polymer. In
addition, the modifying compound may contain more than one complementary
reactable group. By "complementary", we mean that the modifying compound
and the latex polymer become chemically bound by the reactive interaction
of the respective reactable groups.
A preferred modifying compound is an amphiphilic compound having ionizable
or acid-base reactable groups. Useful amphiphilic compounds have both
hydrophobic and hydrophilic groups. The hydrophobic portion of the
amphiphilic compound must contain at least 4 carbon atoms, and can be
branched, straight chain, aromatic, saturated or unsaturated. The
hydrophilic portion of the amphiphilic compound is water soluble and may
include polyoxyethylene, polyoxypropylene, polyacrylamide, or polyvinyl
alcohol. The weight average molecular weight, M.sub.w, of the amphiphilic
compound is less than about 10,000.
Useful amphiphilic compounds may include quaternary ammonium salts, such as
for example, quaternary salt of Ethomeen.RTM. 0/25 supplied by Akzo
Chemicals Inc. This salt is a quaternary polyethoxylated ammonium salt
with the formula C.sub.18 H.sub.35 (CH.sub.3)N(CH.sub.2 CH.sub.2 O).sub.x
H(CH.sub.2 CH.sub.2 O).sub.y H(I) where x+y=15 and a molecular weight of
about 942. The quaternary salt contains a positively charged nitrogen
group which can form a complementary pair with a latex polymer containing
an anionic group, such as for example, a carboxylate group.
Triton.RTM. RW-150 supplied by Union Carbide Company with the formula
t-C.sub.12-14 NH(CH.sub.2 CH.sub.2 O).sub.15 H is a polyethoxylated amine
which is another useful amphiphilic compound. A preferred amphiphilic
compound is a tertiary polyethoxylated amine with the formula C.sub.18
H.sub.37 N(CH.sub.2 CH.sub.2 O).sub.x H(CH.sub.2 CH.sub.2 O).sub.y
H(x+y=15) and a molecular weight of about 929 (Ethomeen.RTM. 18/25
supplied by Akzo Chemical Inc.). The amine base is the second reactable
group which is combined and reacted with a latex containing an acid as the
first reactable group.
A preferred covalently bonded pair of complementary reactable groups is a
JEFFAMINE.RTM. ED-600 (supplied by the Texaco Chemical Company) modifying
compound reacted with an acetoacetate containing latex. (see Example 13).
JEFFAMINE.RTM. ED-600 is a polyether diamine based on a predominately
polyethylene oxide backbone. The amine (JEFFAMINE.RTM. ED-600) is the
second reactable group which is reacted with a latex containing
acetoacetate as the first reactable group.
There are several ways to combine the latex polymer and selected modifying
compound in the aqueous coating. An aqueous coating can be formulated with
the latex polymer, and then the modifying compound can be added as an
additive to the aqueous coating. It is preferred that the modifying
compound is first combined with the latex polymer, stirred until blended
with the latex polymer, such as for example, on the order of at least 10
minutes. After stirring, the latex polymer and modifying compound may be
left to equilibrate, such as for example, overnight. Then an aqueous
coating is formulated with the mixture of the modifying compound and the
latex.
The modifying compound containing the second reactable group is added to
the latex polymer at the level of from 0.01 to about 10 molar equivalent,
based on the molar equivalent of the first reactable group in the latex
polymer. More preferably, the modifying compound is added to the latex
polymer at the level of from 0.1 to 1.0 molar equivalent.
The concentration of the modifying compound in the final aqueous coating is
from 0.1 to 10% by weight solids, based on the total weight solids of the
latex polymer in the aqueous coating, preferably is from 2 to 10% weight
solids, and most preferably is from 4 to 8% weight solids.
In general, a gallon of emulsion paint contains from about 0.5 to 3 pounds
of latex polymer solids and from about 0.2 to about 5 pounds of
finely-divided pigment. Typical pigments are titanium dioxide and other
titanium pigments, white lead, zinc oxide, zinc sulfide, barium sulfate,
calcium carbonate, lithopone, silica, talc, mica, clays, iron oxide,
carbon black, cadmium sulfide, toluidene red, chrome orange, chrome
yellow, chrome green, and others known in the art. Other synthetic
pigments may also be included such as for example, ROPAQUE.RTM. opaque
polymer. Sometimes driers are added, such as for example, cobalt and
manganese, to coatings that contain unsaturated polymers which cure by
oxidation. Minor amounts of other coatings additives may also be included
in the paint formulations, such as for example, defoamers, anti-foams,
coalescents, surfactants, dispersants, mildewcides, thickeners, wetting
agents, biocides, and the like.
The open time of the aqueous coating may be measured by brush applying the
coating to a substrate and determining the time when additional fresh
paint does not melt in or blend well visually with a previously applied,
wet coated substrate. By this, we mean that the test can be done by
overlapping a second coat over a first coat at three minute intervals (see
Illustrative Example 3), and determining the maximum time (open time)
before which flow, leveling, and brush marks are noticeably different in
the overlapped area compared to the first coat. The test can also be done
by painting a second coat parallel to and over the first coat at 5 minute
intervals, and determining the maximum time (open time) at which the
second coat of paint does not show defects in the dried coating including
brush marks, loss of gloss, and surface damage (see Example 6). In another
open time method, crosses in the shape of an X are etched into a freshly
coated substrate, and then a second coat of paint is brushed over and
perpendicular to a cross etched in the first coat at 3 minute intervals
(See Example 9). The open time for this test is defined as the maximum
time at which the etched crosses are not visible.
The following examples are intended to illustrate the method of improving
the open time of an aqueous coating, to which this invention is directed.
EXAMPLE 1
Preparation of Latex/Modifying Compound Blend:Sample 1
26.45 grams of a modifying compound (Ethomeen.RTM. 18/25 at 33% by weight
solids) was added to 519.65 grams of an aqueous emulsion (41.4% by weight
solids) containing a 49% 2-Ethyl-hexyl acrylate(EHA)/23% Styrene (St)/27%
Acrylonitrile(AN)/1.0% Methacrylic acid (MAA) latex The methacrylic acid
was the first reactable group and the amine (Ethomeen.RTM. 18/25) was the
second reactable group. At room temperature, the mixture was stirred for
10 minutes and equilibrated overnight to allow the first reactable group
and second reactable group to react.
EXAMPLE 2
Preparation of the Aqueous Coating with Sample 1
A control paint was made in a standard paint formulation as shown with a
49%EHA/23%St/27%AN/1.0%MAA emulsion polymer without a modifying compound
(41.4% by weight solids). Sample 1 was evaluated in the same paint
formulation.
______________________________________
Amount (parts by weight
Paint containing
Ingredient Control Paint
Sample 1
______________________________________
Mix in Cowls Dissolver
Propylene Glycol
70 70
Dispersant 35 35
Defoamer 4.2 4.2
Biocide 1.7 1.7
Neutralizing Base
0.8 0.8
Polyurethane Thickener
29.4 29.4
Rutile Titanium Dioxide
250.0 250.0
Water 38.9 15.6
Latex 547.8 --
Sample 1 Latex Blend
-- 545.7
Coalescent 22.7 22.7
Defoamer 2.5 2.5
Neutralizing Base
1.4 0.6
Polyurethane Thickener
38.0 56.7
______________________________________
Pigment Volume Concentration = 22.68%
Volume Solids = 33.07%
EXAMPLE 3
Measurement of Open Time for the Paint Containing Sample 1
Open time was measured as follows. The control paint and the paint
containing Sample 1 were both separately brushed out lengthwise on half of
a coated paper chart (12H Spreading Rate Leneta Chart) using a natural
spread rate. At three minute intervals, a second coat of each test paint
was brushed lengthwise, in separate sections, from an unpainted area of
the chart into the first coat to overlap at least half of the first coat.
The paints were dried at 70.degree. F. and 50% relative humidity for 24
hours. The open time was defined as the maximum time at which the second
coat of paint blended in well with the first coat at the overlap. By this,
we mean that this maximum time (open time) was established as the last
three minute interval before which flow, leveling, and brushmarks of the
overlapped area were noticeably different than the first coat.
The results of the open time test for the control paint and the paint
containing Sample 1 are shown in Table 1:
TABLE 1
______________________________________
OPEN TIME RESULTS
Control Paint
Paint containing Sample 1
______________________________________
Open time (minutes)
3 12
______________________________________
The control paint had an open time of 3 minutes and noticeable differences
in flow, leveling, and brush marks in the overlapped area compared to the
first coat at 6 minutes and longer. The paint made with Sample 1
(EHA/St/AN latex blended with Ethomeen.RTM. 18/25) had an open time of 12
minutes and noticeable differences in flow, leveling, and brush marks in
the overlapped area compared to the first coat at 15 minutes and longer.
EXAMPLE 4
Preparation of Latex/Modifying Compound Blend: Sample 2
Preparation of the Quaternary Salt of Ethomeen.RTM. 0/25
To 102 grams of Ethomeen.RTM. 0/25 was added 29.3 grams of methyl iodide.
The mixture was stirred and heated to 80.degree. C. for 6 hours. The
resulting product was the quaternary salt of Ethomeen.RTM. 0/25.
48.56 grams of a modifying compound (quaternary salt of Ethomeen.RTM. 0/25
at 19.35% by weight solids) was added to 469.74 grams of an aqueous
emulsion (50.0% by weight solids) containing a 46% Butyl acrylate (BA)/53%
Methyl methacrylate (MMA)/1.0% Methacrylic acid (MAA) latex. At room
temperature, the mixture was stirred for 10 minutes and equilibrated
overnight to allow the first reactable group and second reactable group to
react.
EXAMPLE 5
Preparation of the Aqueous Coating with Sample 2
A control paint was made in the paint formulation as shown with a
46%BA/53%MMA/1.0%MAA emulsion polymer without a modifying compound (50.0%
by weight solids). Sample 2 was evaluated in the same formulation with the
exception of the addition of cobalt and manganese driers to the paint.
______________________________________
Amount (parts by weight
Paint containing
Ingredient Control Paint
Sample 2
______________________________________
Mix in Cowls Dissolver
Propylene Glycol
72 72
Dispersant 13.9 13.9
Defoamer 1.0 1.0
Rutile Titanium Dioxide
267.6 267.6
Water 5.0 5.0
Water 168.9 62.1
Latex 489.1 --
Sample 2 Latex Blend
-- 518.3
Coalescent 24.5 24.4
Aqueous Cobalt Drier
-- 4.9
Aqueous Manganese Drier
-- 4.9
Defoamer 1.0 1.0
Polyurethane Thickener
25.6 98.2
______________________________________
Pigment Volume Concentration = 23.65%
Volume Solids = 33.95%
EXAMPLE 6
Measurement of Open Time for the Paint Containing Sample 2
Open time was measured as follows. Each of the control paint and paint
containing Sample 2 was brushed out lengthwise on a sealed chart using a
natural spread rate. After 5, 10, 15, and 20 minute intervals, a second
coat of each test paint was brushed out on 1/4 of the chart, parallel to
and on top of the first coat in separate sections of the chart. The paints
were dried at 70.degree. F. and 65% relative humidity. Open time was
defined as the maximum time at which the second coat of paint did not show
defects in the dried coating including brush marks, loss of gloss, and
surface damage. By surface damage, we mean that the dried coating was
destroyed or ripped.
The results of the open time test for the control paint and the paint
containing Sample 1 are shown in Table 2.
TABLE 2
______________________________________
OPEN TIME RESULTS
Control Paint
Paint containing Sample 2
______________________________________
Open time (minutes)
<5 15
______________________________________
The control paint had an open time of less than 5 minutes and had defects
in the dried second coat at 5 minutes and longer. The paint made with
Sample 2 (BA/MMA/MAA latex blended with the quaternary salt of
Ethomeen.RTM. 0/25) had an open time of 15 minutes and had defects in the
dried second coat at 20 minutes and longer.
EXAMPLE 7
Preparation of Latex/Modifying Compound Blend: Sample 3
27.9 grams of a modifying compound (TRITON.RTM. RW-150 at 33% by weight
solids) was added to 500 grams of an aqueous emulsion (46% by weight
solids) containing a 46% Butyl acrylate (BA)/53% Methyl methacrylate
(MMA)/1.0% Methacrylic acid (MAA) latex. At room temperature, the mixture
was stirred for 10 minutes and equilibrated overnight to allow the first
reactable group and second reactable group to react.
EXAMPLE 8
Preparation of the Aqueous Coating with Sample 3
A control paint was made in the paint formulation as shown with a
46%BA/53%MMA/1.0%MAA emulsion polymer without a modifying compound (46% by
weight solids). Sample 3 was formulated in the same formulation.
______________________________________
Amount (parts by weight
Paint containing
Ingredient Control Paint
Sample 3
______________________________________
Mix in Cowls Dissolver
Propylene Glycol
20.3 20.3
Dispersant 35 35
Defoamer 4.2 4.2
Biocide 1.7 1.7
Methyl Carbitol 16.8 16.8
Neutralizing Base
0.8 0.8
Polyurethane Thickener
29.4 29.4
Rutile Titanium Dioxide
250 250
Water 110.8 121.5
Latex 519.6 --
Sample 3 Latex Blend
-- 536.4
Coalescent 17.4 19.4
Defoamer 2.6 2.6
Neutralizing Base
2.5 --
Polyurethane Thickener
39.4 53.5
______________________________________
Pigment Volume Concentration = 22.68%
Volume Solids = 33.07%
EXAMPLE 9
Measurement of Open Time for the Paint Containing Sample 3
Open time was measured as follows. Each of the control paint and paint
containing Sample 3 (46%BA/53%MMA/1.0%MAA latex blended with TRITON.RTM.
RW-150) was brushed out lengthwise on approximately 2 inch width section
of a sealed chart. Crosses in the shape of an X were immediately etched in
the paint film from top to bottom using a tongue depressor. At three
minute intervals, a second coat of each test paint was brushed over and
perpendicular to a cross etched in the first coat. The open time was
defined as the maximum time at which the etched crosses were not visible.
By this we mean that this maximum time (open time) is the last three
minute interval before which the etched cross was visible in the dried
paint film.
The results of the open time test for the control paint and the paint
containing Sample 3 are shown in Table 3.
TABLE 3
______________________________________
OPEN TIME RESULTS
Control Paint
Paint containing Sample 3
______________________________________
Open time (minutes)
3 9
______________________________________
The control paint had an open time of 3 minutes and the crosses were
visible in dried coating at 6 minutes and longer. The paint made with
Sample 3 had an open time of 9 minutes and the etched crosses were visible
in the dried coating at 12 minutes and longer.
EXAMPLE 10
Preparation of Latex/Modifying Compound Blend: Sample 4
a) Preparation of Aldehyde-terminated Polyvinyl Alchohol
To 600 grams of a 20% by weight solution of polyvinyl alcohol in water
(Airvol.RTM. 203 supplied by Air Products), was added 16.0 grams of sodium
periodate. The mixture was stirred at room temperature for 3 hours to form
an aldehyde-terminated (second reactable group) polyvinyl alcohol.
b) Combination of Aldehyde-terminated Polyvinyl Alcohol with
BA/MMA/AAEM/MAA latex
115 grams of a 20% by weight solution of aldehyde-terminated polyvinyl
alcohol was added to 400 grams of an aqueous emulsion (45.8% by weight
solids) containing a 39% Butyl acrylate (BA)/50% Methyl methacrylate
(MMA)/9% Acetoacetoxy ethyl methacrylate (AAEM)/2% Methacrylic acid (MAA)
latex. The AAEM was the first reactable group. The mixture was stirred at
room temperature for 6 hours to allow the complementary aldehyde and
acetoacetate groups to react.
EXAMPLE 11
Preparation of the Aqueous Coating with Sample 4
A control paint was made in the paint formulation as shown with a
39%BA/50%MMA/9%AAEM/2.0%MAA emulsion polymer without a modifying compound
(46.2% by weight solids). Sample 4 was formulated in the same formulation.
______________________________________
Amount (parts by weight
Paint containing
Ingredient Control Paint
Sample 4
______________________________________
Mix in Cowls Dissolver
Propylene Glycol
70 70
Dispersant 35 35
Defoamer 4.2 4.2
Biocide 1.7 1.7
Neutralizing Base
0.8 0.8
Polyurethane Thickener
29.4 29.4
Rutile Titanium Dioxide
250.0 250.0
Water 87.0 34.4
Latex 525.6 --
Sample 4 Latex Blend
-- 598.4
Coalescent 17.0 17.6
Defoamer 2.5 2.5
Neutralizing Base
-- 1.7
Polyurethane Thickener
33.0 19.7
______________________________________
Pigment Volume Concentration = 22.68%
Volume Solids = 33.07%
EXAMPLE 12
Measurement of the Open Time of the Paint Containing Sample 4
Open time was measured using the procedure described in EXAMPLE 3. The
results are shown in Table 4.
TABLE 4
______________________________________
OPEN TIME RESULTS
Control Paint
Paint containing Sample 4
______________________________________
Open time (minutes)
3 6-9
______________________________________
The control paint had an open time of 3 minutes and noticeable differences
in flow, leveling, and brush marks in the overlapped area compared to the
first coat at 6 minutes and longer. The paint made with Sample 4
(BA/MMA/AAEM/MAA emulsion blended with an aldehyde-terminal polyvinyl
alcohol) had an open time of from 6 minutes to about 9 minutes. By this,
we mean that there was no noticeable differences in flow, leveling, and
brush marks in the overlapped area compared to the first coat at 6
minutes, and there were slight differences in flow, leveling, and brush
marks at 9 minutes. At 12 minutes and longer, there were distinct
differences in flow, leveling, and brush marks in the overlapped area
compared to the first coat.
EXAMPLE 13
Preparation of Latex/Modifying Compound Blend:Sample 5
25.6 grams of a modifying compound (JEFFAMINE.RTM. ED-600 at 45.6% by
weight solids) was added to 511.6 grams of an aqueous emulsion (45.6% by
weight solids) containing a 39% Butyl acrylate (BA)/50% Methyl
methacrylate (MMA)/9% Acetoacetoxy ethyl methacrylate (AAEM)/2%
Methacrylic acid (MAA) latex. At room temperature, the mixture was stirred
for 10 minutes and equilibrated overnight to allow the first and second
reactable groups to react.
EXAMPLE 14
Preparation of the Aqueous Coating with Sample 5
A control paint was made in the paint formulation shown with a
39%BA/50%MMA/9%AAEM/2%MAA emulsion polymer without a modifying compound
(45.6% by weight solids). Sample 5 was formulated in the same formulation.
______________________________________
Amount (parts by weight
Paint containing
Ingredient Control Paint
Sample 5
______________________________________
Mix in Cowls Dissolver
Propylene Glycol
70 70
Dispersant 35 35
Defoamer 4.2 4.2
Biocide 1.7 1.7
Neutralizing Base
0.8 0.8
Polyurethane Thickener
29.4 29.4
Rutile Titanium Dioxide
250.0 250.0
Water 78.8 70.0
Latex 532.6 --
Sample 5 Latex Blend
-- 537.2
Coalescent 24.2 24.2
Defoamer 2.5 2.5
Neutralizing Base
3.0 2.0
Polyurethane Thickener
24.8 26.0
______________________________________
Pigment Volume Concentration = 22.68%
Volume Solids = 33.07%
EXAMPLE 15
Measurement of Open Time for the Paint Containing Sample 5
Open time was measured using the procedure described in EXAMPLE 3. The
results are shown in Table 5.
TABLE 5
______________________________________
OPEN TIME RESULTS
Control Paint
Paint containing Sample 5
______________________________________
Open time (minutes)
3 >12
______________________________________
The control paint had an open time of 3 minutes and noticeable differences
in flow, leveling, and brush marks in the overlapped area compared to the
first coat at 6 minutes and longer. The paint made with Sample 5
(BA/MMA/AAEM/MAA emulsion blended with JEFFAMINE.RTM. ED-600) had an open
time greater than 12 minutes. By this, we mean that there were no
noticeable differences in flow, leveling, and brush marks in the
overlapped area compared to the first coat at 12 minutes. Since the test
method was run up to 12 minutes, the open time of the paint made with
Sample 5 occurred after 12 minutes.
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